Pulse generator



' March 30,1948. KNOOP, JR 2,438,705

PULSE-GENERATOR Filed Dec. 27, 1943 INVENTOR. I

Patented Mar. 30, 1948 UNlTEDf/STATES 2P5 PULSE GENERATOR Walter A. Knoop, Jr., Packanack Lake, N. J assignor to Allen B. Du Mont Laboratories, Inc., Passaic, N. J a corporation of Delaware Application December 27, 1943, Serial No. 515,675

4 Claims. 1

This invention relates to a generator of electrical pulses. It relates more particularly to a device for generating pulses of short duration in such a Way that the repetition or rate of generating such pulses can be easily regulated and widely varied.

By this invention the necessity of employing a large number of vacuum tubes for generating electrical pulses is obviated and at the same time the repetition rate can be varied very easily over wide ranges without requiring a large power supply, so that pulses of narrow widths and high amplitude can be generated economically.

In carrying out the invention a cathode-ray tube is used which is provided with deflection plates for controlling the electron beam and the pulses are generated by this beam.

The invention may be understood from the description in connection with the accompanying drawing, in which:

Fig. 1 is a side view of an illustrative embodiment of the invention and Fig. 2 is an end view of a modification.

In the drawing, reference character I indicates a cathode-ray tube of a well known type which is provided with the usual cathode 2, grid 3, first anode 4, second anode 5, and pairs of deflection plates 6 and I at right angles to eachother, to generate the cathode-ray beam 8 and cause its end to move in a circular path. Electromagnetic control of this beam may be used instead of electrostatic means, as indicated.

A radially extending wire I0, which may, for example, be about a millimeter in diameter, is located near the large end of tube I at right angles to the axis of this tube. It is hermetically sealed through the tubev I, as indicated at II, and is connected to a source of positive potential, which may be about 4000 volts, through a resistance I2 that may be 2 megohms, or less than that for bet! ter frequency response.

The inside of the large end of tube I is coated with a layer I --of conducting material which is connected by lead I6, sealed through the glass as shown at H, to a source of positive potential which may, for example, be 500 volts. The lead I6 is connected to ground through a low impedance I8.

The operation is as follows:

The cathode-ray beam '8 is caused to swing around by out-of-phase alternating electrical potentials applied to deflecting means 6 and I in the usual way so that the end of this beam is caused to move around on the layer I5 of positively charged conducting material so that no negative charge accumulates.

interval of time. The frequency of these pulses of current depends upon the rate at which this beam is caused to swing around by the out-ofphase alternating'current potentials applied to plates 4 and 5. These current pulses flowing. through resistance i2 may be of the order of 500 microamperes. They cause sudden potential. drops at the point 20. These sudden changes inpotential may be amplified, for example, by the amplifier indicated at A, or in any other suitable way.

The duration of the pulses caused by the beam 8 crossing the wire I0 depends upon the size of the beam, its angular velocity, and the size of the wire I0. The repetition rate of these pulses depends upon the number of times the beam sweeps: around per unit of time, being twice as great when the wire I0 is long enough and so located that the beam strikes it twice per revolution. The frequency may be increased by using more radially extending wires if as shown in plan View in Fig. 10 connected to the point 20 by circular wire 2I. The beam 8 sweeps across the wires ID as indicated by the path 22.

The changes in potential at the point 20 caused by the beam 8 striking the wire II] or wires I0 may be amplified as indicated by the amplifier A,

' and used for whatever purposes may be desired.

These pulses may be used wherever needed, as, for example, to control the duration of oscillation of a controlled oscillator.

What is claimed is:

1. A device for generating electrical pulses which comprises a cathode-ray tube having a layer of positively charged conducting material on the inside face thereof connected to ground through a resistance, a wire in said tube in front .of said layer extending outside of said tube and connected to a source of positive potential and means to cause the beam of said tube to turn and strike said wire twice per revolution of said beam.

2. The device of claim 1 in which said wire is connected to said source of positive material through a high resistance.

3. The device of claim 1 in which said layer is insulated from said wire.

4. The device of claim 1 in which said wire is radially disposed in said tube.

WALTER A. KNOOP, JR.

(References on following page) 3 Number REFERENCES CITED 2,171,150 The following references are of record in the 2 193 539 file of this patent: 2,265,848 5 2,273,793 UNITED STATES PATENTS 2,2 90 651 Number Name Date 1,763,309 Hough -Jnne .19, ,1 930 1,896,747 Hund .fieb. 7,1933 .Number 1,932,637 Richardson Oct. 31, 1 1 643,163

2,057,773 Finch Oct. 20, 1936 Name Date Shelby Aug. 29, 1939 Shelby Mar. 12, 1940 Lewis Dec. 9, 1941 Ekstrand Feb. 17, 1942 Peck July 21, 1942 FOREIGN PATENTS Country Date Germany Mar. 30, 1937 

